Description

    TEX is a typesetting language developed by Donald Knuth. It takes
   source text together with a few typesetting instructions and produces,
   one hopes, a beautiful document. Beautiful documents use
   double-left-quote and double-right-quote to delimit quotations, rather
   than the mundane " which is what is provided by most keyboards.
   Keyboards typically do not have an oriented double-quote, but they do
   have a left-single-quote ` and a right-single-quote '. Check your
   keyboard now to locate the left-single-quote key ` (sometimes called
   the "backquote key") and the right-single-quote key ' (sometimes
   called the "apostrophe" or just "quote"). Be careful not to confuse
   the left-single-quote ` with the "backslash" key \. TEX lets the user
   type two left-single-quotes `` to create a left-double-quote and two
   right-single-quotes '' to create a right-double-quote. Most typists,
   however, are accustomed to delimiting their quotations with the
   un-oriented double-quote ".
   
   If the source contained
"To be or not to be," quoth the bard, "that is the question."

   then the typeset document produced by TEX would not contain the
   desired form: "To be or not to be," quoth the bard, "that is the
   question." In order to produce the desired form, the source file must
   contain the sequence:
``To be or not to be,'' quoth the bard, ``that is the question.''

   You are to write a program which converts text containing double-quote
   (") characters into text that is identical except that double-quotes
   have been replaced by the two-character sequences required by TEX for
   delimiting quotations with oriented double-quotes. The double-quote
   (") characters should be replaced appropriately by either `` if the "
   opens a quotation and by '' if the " closes a quotation. Notice that
   the question of nested quotations does not arise: The first " must be
   replaced by ``, the next by '', the next by ``, the next by '', the
   next by ``, the next by '', and so on.

Input

Input will consist of several lines of text containing an even number
   of double-quote (") characters. Input is ended with an end-of-file
   character. The text must be output exactly as it was input except
   that:
     * the first " in each pair is replaced by two ` characters: `` and
     * the second " in each pair is replaced by two ' characters: ''.

Output

Sample Input

"To be or not to be," quoth the Bard, "that
is the question".
The programming contestant replied: "I must disagree.
To `C' or not to `C', that is The Question!"

Sample Output

``To be or not to be,'' quoth the Bard, ``that
is the question''.
The programming contestant replied: ``I must disagree.
To `C' or not to `C', that is The Question!''

HINT

Source

East Central 1994